Should Measures of Health Care Availability Be Based on the Providers or the Procedures? A Case Study with Implications for Rural Colorectal Cancer Disparities

Longer travel times to acute hospitals are associated with lower likelihood of cancer screening receipt among rural-dwelling adults in the U.S. South

PURPOSE

Given rural hospitals' role in providing outpatient services, we examined the association between travel burdens and receipt of cancer screening among rural-dwelling adults in the U.S. South region.

METHODS

First, we estimated network travel times and distances to access the nearest and second nearest acute care hospital from each rural census tract in the U.S. South. After appending the Centers for Disease Control's PLACES dataset, we fitted generalized linear mixed models.

RESULTS

Longer distances to the second nearest hospital are negatively associated with breast, colorectal, and cervical cancer screening receipt among eligible rural-dwelling adults. Rural-dwelling women in counties with 1 closure had reduced likelihood of breast cancer screening. Residence in a partial- or whole-county Health Professional Shortage Area (HPSA) was negatively associated with cancer screening receipt. Specialist (OB/GYN and gastroenterologist) supply was positively associated with receipt of cancer screening. Uninsurance was positively associated with cervical and breast cancer screening receipt. Medicaid expansion was associated with increased breast and cervical cancer screening.

CONCLUSIONS

Rural residents in partial-county primary care HPSAs had the lowest rates of breast, cervical, and colorectal cancer screening, compared with whole-county HPSAs and non-shortage areas. These residents also faced the greatest distances to their nearest and second nearest hospital. This is notable because rural residents in the South face greater travel burdens for cancer care compared with residents in other regions. Finally, the positive association between uninsurance and breast and cervical cancer screening may reflect the CDC's National Breast and Cervical Cancer Early Detection Program's effectiveness.

Rural-Urban Disparities in Cancer Outcomes: Opportunities for Future Research

Cancer care disparities among rural populations are increasingly documented and may be worsening, likely because of the impact of rurality on access to state-of-the-art cancer prevention, diagnosis, and treatment services, as well as higher rates of risk factors such as smoking and obesity. In 2018, the American Society of Clinical Oncology undertook an initiative to understand and address factors contributing to rural cancer care disparities. A key pillar of this initiative was to identify knowledge gaps and promote the research needed to understand the magnitude of difference in outcomes in rural vs nonrural settings, the drivers of those differences, and interventions to address them. The purpose of this review is to describe continued knowledge gaps and areas of priority research to address them. We conducted a comprehensive literature review by searching the PubMed (Medline), Embase, Web of Science, and Cochrane Library databases for studies published in English between 1971 and 2021 and restricted to primary reports from populations in the United States and abstracted data to synthesize current evidence and identify continued gaps in knowledge. Our review identified continuing gaps in the literature regarding the underlying causes of rural-urban disparities in cancer outcomes. Rapid advances in cancer care will worsen existing disparities in outcomes for rural patients without directed effort to understand and address barriers to high-quality care in these areas. Research should be prioritized to address ongoing knowledge gaps about the drivers of rurality-based disparities and preventative and corrective interventions.

Spatial accessibility to colonoscopy and its role in predicting late-stage colorectal cancer

OBJECTIVE

To better determine the relationship between spatial access to colonoscopy and colorectal cancer (CRC) outcomes, our objective was to examine the agreement of the classic, enhanced, and variable two-step floating catchment area (2SFCA) methods in evaluating spatial access to colonoscopy and to compare the predictive validity of each method related to late-stage CRC. 2SFCA methods simultaneously consider supply/demand of services and impedance (ie, travel time).

DATA SOURCES

Colonoscopy provider locations were obtained from the South Carolina Ambulatory Surgery Database. ZIP code tabulation area (ZCTA) level population estimates and area-level poverty level were obtained from the American Community Survey. Rurality was determined by the United States Department of Agriculture's Rural-Urban Commuting Area codes. Individual-level CRC data were obtained from the South Carolina Central Cancer Registry.

STUDY DESIGN

Using the classic, enhanced, and variable 2SFCA methods, we calculated ZCTA-level spatial access to colonoscopy. We assessed agreement between the three methods by calculating Spearman's rank coefficients and weighted Kappas (Κ). Global and Local Moran's I were used to assess spatial clustering of accessibility scores across 2SFCA methods. We performed multilevel logistic regression analyses to examine the association between spatial accessibility to colonoscopy, area- and individual-level factors, and late-stage CRC.

PRINCIPAL FINDINGS

We found strong agreement (Weighted Κ = 0.82; 95% CI = 0.79-0.86) and identified similar clustering patterns with the classic and enhanced 2SFCA methods. There was negligible agreement among the classic/enhanced 2SFCA and the variable 2SFCA. Across all 2SFCA methods, regression models showed that spatial access to colonoscopy, rurality, and poverty level were not associated with greater odds of late-stage CRC, though Black race was associated with late-stage CRC across all models.

CONCLUSIONS

None of the 2SFCA methods showed an association with late-stage CRC. Future studies should explore which elements (spatial or nonspatial) of access to care have the greatest impact on CRC outcomes.

Estimating health service utilization potential using the supply-concentric demand-accumulation spatial availability index: a pulmonary rehabilitation case study

The potential for a population at a given location to utilize a health service can be estimated using a newly developed measure called the supply-concentric demand accumulation (SCDA) spatial availability index. Spatial availability is the amount of demand at the given location that can be satisfied by the supply of services at a facility, after discounting the intervening demand among other populations that are located nearer to a facility location than the given population location. This differs from spatial accessibility measures which treat absolute distance or travel time as the factor that impedes utilization. The SCDA is illustrated using pulmonary rehabilitation (PR), which is a treatment for people with chronic obstructive pulmonary disease (COPD). The spatial availability of PR was estimated for each Census block group in Georgia using the 1105 residents who utilized one of 45 PR facilities located in or around Georgia. Data was provided by the Centers for Medicare & Medicaid Services. The geographic patterns of the SCDA spatial availability index and the two-step floating catchment area (2SFCA) spatial accessibility index were compared with the observed PR utilization rate using bivariate local indicators of spatial association. The SCDA index was more associated with PR utilization (Morans I = 0.607, P < 0.001) than was the 2SFCA (Morans I = 0.321, P < 0.001). These results suggest that the measures of spatial availability may be a better way to estimate the health care utilization potential than measures of spatial accessibility.

Using spatially adaptive floating catchments to measure the geographic availability of a health care service: Pulmonary rehabilitation in the southeastern United States

A spatially adaptive floating catchment is a circular area that expands outward from a provider location until the estimated demand for services in the nearest population locations exceeds the observed number of health care services performed at the provider location. This new way of creating floating catchments was developed to address the change of spatial support problem (COSP) by upscaling the availability of the service observed at a provider location to the county-level so that its geographic association with utilization could be measured using the same spatial support. Medicare Fee-for-Service claims data were used to identify beneficiaries aged ≥ 65 years who received outpatient pulmonary rehabilitation (PR) in the Southeastern United States in 2014 (n = 8798), the number of PR treatments these beneficiaries received (n = 132,508), and the PR providers they chose (n = 426). The positive correlation between PR availability and utilization was relatively low, but statistically significant (r = 0.619, p < 0.001) indicating that most people use the nearest available PR services, but some travel long distances. SAFCs can be created using data from health care systems that collect claim-level utilization data that identifies the locations of providers chosen by beneficiaries of a specific health care procedure.